1. Field of the Invention
The present invention relates to a Hall element and a magnetic sensor system and, more particularly, to a new Hall element adapted for miniaturization and a magnetic sensor system employing the same.
2. Description of the Background Art
Prior to the description of a conventional magnetic sensor system, a description is given of a Hall effect. FIG. 13 is a conceptual diagram for describing the Hall effect. Referring to FIG. 13, when a vertical magnetic field H.sub.Z is applied to a long and narrow plate through which a uniform current I.sub.X flows in a direction of the X-axis, an electromotive force Ey is generated in a direction Y vertical to H.sub.Z, I.sub.X and a current flows in a conductor ACB connected at the external portion. This phenomenon is called the Hall effect, which is used in a simple magnetic field detector, a direction detector and the like.
FIG. 14 is a conceptual diagram of a magnetic sensor system using the conventional Hall device. The Hall devices 10 are arranged on the X-Y plane, Y-Z plane, and the Z-X plane. The output terminals of the respective Hall devices are electrically connected to an A/D converter 12 through a switch 11 and the A/D converter 12 is electrically connected to a digital signal processing circuit 13. Next, a description is given of a structure of the conventional Hall device 10.
FIG. 15 is a perspective view of the conventional Hall device, FIG. 16 is a perspective view taken along a direction of an arrow XVI in FIG. 15, FIG. 17 is a view taken along a direction of an arrow XVII in FIG. 15, and FIG. 18 is a view taken from a direction of an arrow XVIII in FIG. 15. Referring to these figures, the Hall device 10 comprises a P type semiconductor substrate 14. The P type semiconductor substrate 14 has a main surface 14a, a back surface 14b and a side surface 14c. An N type semiconductor region 7 is provided in the P type semiconductor substrate 14. A pair of electrodes 9 are provided so as to sandwich the N type semiconductor region 7 between both sides. In addition, a pair of Hall voltage detecting electrodes 8 and 8 are provided so as to sandwich the N type semiconductor region 7 in a direction vertical to the arrangement direction of the above-described pair of electrodes 9 and 9. Now, referring to these figures, a description is given of an operation of the Hall device. When a current flows between the pair of electrodes 9 and 9 and a magnetic flux component B is introduced from a direction of an arrow XVI (that is, a direction vertical to the substrate) into the N type semiconductor region 7, the Hall electromotive force is generated between the Hall voltage direction electrodes 8 and 8 by the Hall effect.
Referring to FIG. 14 again, the conventional magnetic sensor system is constituted by arranging the above-described Hall devices on the X-Y plane, on the Y-Z plane and on the Z-X plane. The Hall device 10 on the X-Y plane detects a component B.sub.Z of the Z-axis direction of the magnetic flux, the Hall device 10 on the Y-Z plane detects a component B.sub.X of the X-axis direction of the magnetic flux and the Hall device 10 on the Z-X plane detects a component B.sub.Y of the Y-axis direction of the magnetic flux. The respective magnetic flux components of the directions are separately inputted to the A/D converter 12 by the switch 11 and then, its size, direction and the like are calculated by the digital signal processing circuit 13.
Next, a description is given of a method of manufacturing the conventional Hall device.
FIG. 19A to 19F are perspective views of the conventional Hall device at different steps of a method of manufacturing the same. Referring to FIG. 19A, a resist 15 is applied to a P type semiconductor substrate 14. Referring to FIG. 19B, the resist 15 at the portion in which current electrodes and Hall voltage detecting electrodes are formed is opened. Referring to FIG. 19C, n.sup.+ impurity ions 16 are then implanted using the resist 15 as a mask and, thereafter, the N.sup.+ impurity ions are diffused in the P type semiconductor substrate 14. Next, the resist 15 is removed. As a result, the current electrode and the Hall detecting electrodes are formed. Referring to FIG. 19D, a resist 17 is applied to the whole surface of the P type semiconductor substrate 14 and the portion of the resist 17 sandwiched by the current electrode and the Hall voltage detecting electrode is opened. Referring to FIG. 19E, N type impurity ions 18 are then implanted using the resist 17 as a mask and, thereafter, the n.sup.+ impurity ions are diffused in the P type semiconductor substrate 14. As a result, referring to FIG. 19F, a pair of current electrodes 9 and 9, a pair of Hall voltage rejecting electrodes 8 and 8 and an N type semiconductor region 7 sandwiched by the pair of current electrodes 9 and 9 and the pair of Hall voltage detecting electrodes 8 and 8 are formed.
Since the conventional Hall device and magnetic sensor system are structured as described above, it is necessary to arrange the Hall device in three directions as shown in FIG. 14. Therefore, there was a disadvantage that the size of the device became large, and the larger the size of the device was, the bigger power consumption was caused.